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Nuruzzaman M, Sato M, Okamoto S, Hoque M, Shea DJ, Fujimoto R, Shimizu M, Fukai E, Okazaki K. Comparative transcriptome analysis during tuberous stem formation in Kohlrabi (B. oleracea var. gongylodes) at early growth periods (seedling stages). PHYSIOLOGIA PLANTARUM 2022; 174:e13770. [PMID: 36018597 DOI: 10.1111/ppl.13770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 08/18/2022] [Accepted: 08/22/2022] [Indexed: 06/15/2023]
Abstract
Tuberous stem of kohlrabi is an important agronomic trait, however, the molecular basis of tuberization is poorly understood. To elucidate the tuberization mechanism, we conducted a comparative transcriptomic analysis between kohlrabi and broccoli at 10 and 20 days after germination (DAG) as tuberous stem initiated between these time points. A total of 5580 and 2866 differentially expressed transcripts (DETs) were identified between genotypes (kohlrabi vs. broccoli) and growth stages (10 DAG vs. 20 DAG), respectively, and most of the DETs were down-regulated in kohlrabi. Gene ontology (GO) and KEGG pathway enrichment analyses showed that the DETs between genotypes are involved in cell wall loosening and expansion, cell cycle and division, carbohydrate metabolism, hormone transport, hormone signal transduction and in several transcription factors. The DETs identified in those categories may directly/indirectly relate to the initiation and development of tuberous stem in kohlrabi. In addition, the expression pattern of the hormone synthesis related DETs coincided with the endogenous IAA, IAAsp, GA, ABA, and tZ profiles in kohlrabi and broccoli seedlings, that were revealed in our phytohormone analysis. This is the first report on comparative transcriptome analysis for tuberous stem formation in kohlrabi at early growth periods. The resulting data could provide significant insights into the molecular mechanism underlying tuberous stem development in kohlrabi as well as in other tuberous organ forming crops.
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Affiliation(s)
- Md Nuruzzaman
- Graduate School of Science and Technology, Niigata University, Niigata, Japan
- Department of Genetics and Plant Breeding, Bangladesh Agricultural University, Mymensingh, Bangladesh
| | - Masato Sato
- Graduate School of Science and Technology, Niigata University, Niigata, Japan
| | - Satoru Okamoto
- Graduate School of Science and Technology, Niigata University, Niigata, Japan
| | - Mozammel Hoque
- Graduate School of Science and Technology, Niigata University, Niigata, Japan
- Faculty of Agriculture, Sylhet Agricultural University (SAU), Sylhet, Bangladesh
| | - Daniel J Shea
- Graduate School of Science and Technology, Niigata University, Niigata, Japan
| | - Ryo Fujimoto
- Graduate School of Agricultural Science, Kobe University, Kobe, Japan
| | | | - Eigo Fukai
- Graduate School of Science and Technology, Niigata University, Niigata, Japan
| | - Keiichi Okazaki
- Graduate School of Science and Technology, Niigata University, Niigata, Japan
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Xu H, Giannetti A, Sugiyama Y, Zheng W, Schneider R, Watanabe Y, Oda Y, Persson S. Secondary cell wall patterning-connecting the dots, pits and helices. Open Biol 2022; 12:210208. [PMID: 35506204 PMCID: PMC9065968 DOI: 10.1098/rsob.210208] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 04/07/2022] [Indexed: 01/04/2023] Open
Abstract
All plant cells are encased in primary cell walls that determine plant morphology, but also protect the cells against the environment. Certain cells also produce a secondary wall that supports mechanically demanding processes, such as maintaining plant body stature and water transport inside plants. Both these walls are primarily composed of polysaccharides that are arranged in certain patterns to support cell functions. A key requisite for patterned cell walls is the arrangement of cortical microtubules that may direct the delivery of wall polymers and/or cell wall producing enzymes to certain plasma membrane locations. Microtubules also steer the synthesis of cellulose-the load-bearing structure in cell walls-at the plasma membrane. The organization and behaviour of the microtubule array are thus of fundamental importance to cell wall patterns. These aspects are controlled by the coordinated effort of small GTPases that probably coordinate a Turing's reaction-diffusion mechanism to drive microtubule patterns. Here, we give an overview on how wall patterns form in the water-transporting xylem vessels of plants. We discuss systems that have been used to dissect mechanisms that underpin the xylem wall patterns, emphasizing the VND6 and VND7 inducible systems, and outline challenges that lay ahead in this field.
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Affiliation(s)
- Huizhen Xu
- School of Biosciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Alessandro Giannetti
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg C, Denmark
| | - Yuki Sugiyama
- The Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge CB2 1LR, UK
| | - Wenna Zheng
- School of Biosciences, The University of Melbourne, Parkville, Victoria 3010, Australia
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg C, Denmark
| | - René Schneider
- Institute of Biochemistry and Biology, Plant Physiology Department, University of Potsdam, 14476 Potsdam, Germany
| | - Yoichiro Watanabe
- Institute for Research Initiatives, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Yoshihisa Oda
- Department of Gene Function and Phenomics, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
- Department of Genetics, The Graduate University for Advanced Studies, SOKENDAI, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
| | - Staffan Persson
- School of Biosciences, The University of Melbourne, Parkville, Victoria 3010, Australia
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg C, Denmark
- Copenhagen Plant Science Center, University of Copenhagen, 1871 Frederiksberg C, Denmark
- Joint International Research Laboratory of Metabolic and Developmental Sciences, State Key Laboratory of Hybrid Rice, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
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Hearn DJ, O’Brien P, Poulsen SM. Comparative transcriptomics reveals shared gene expression changes during independent evolutionary origins of stem and hypocotyl/root tubers in Brassica (Brassicaceae). PLoS One 2018; 13:e0197166. [PMID: 29856865 PMCID: PMC5983522 DOI: 10.1371/journal.pone.0197166] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 04/27/2018] [Indexed: 11/18/2022] Open
Abstract
Plant succulence provides a classic example of evolutionary convergence in over 40 plant families. If evolutionary parallelism is in fact responsible for separate evolutionary origins of expanded storage tissues in stems, hypocotyls, and roots, we expect similar gene expression profiles in stem and hypocotyl / root tubers. We analyzed RNA-Seq transcript abundance patterns in stem and hypocotyl / root tubers of the Brassica crops kohlrabi (B. oleracea) and turnip (B. rapa) and compared their transcript expression profiles to those in the conspecific thin-stemmed and thin-rooted crops flowering kale and pak choi, respectively. Across these four cultivars, 38,192 expressed gene loci were identified. Of the 3,709 differentially-expressed genes (DEGs) in the turnip: pak choi comparison and the 6,521 DEGs in the kohlrabi: kale comparison, turnips and kohlrabies share a statistically disproportionate overlap of 841 DEG homologs in their tubers (p value < 1e-10). This overlapping set is statistically enriched in biochemical functions that are also associated with tuber induction in potatoes and sweet potatoes: sucrose metabolism, lipoxygenases, auxin metabolism, and meristem development. These shared expression profiles in tuberous stems and root / hypocotyls in Brassica suggest parallel employment of shared molecular genetic pathways during the evolution of tubers in stems, hypocotyls and roots of Brassica crops and more widely in other tuberous plants as well.
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Affiliation(s)
- David J. Hearn
- Department of Biological Sciences, Towson University, Towson, Maryland, United States of America
| | - Patrick O’Brien
- Department of Biological Sciences, Towson University, Towson, Maryland, United States of America
| | - Sylvie M. Poulsen
- Department of Biological Sciences, Towson University, Towson, Maryland, United States of America
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Predicting gene regulatory networks by combining spatial and temporal gene expression data in Arabidopsis root stem cells. Proc Natl Acad Sci U S A 2017; 114:E7632-E7640. [PMID: 28827319 DOI: 10.1073/pnas.1707566114] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Identifying the transcription factors (TFs) and associated networks involved in stem cell regulation is essential for understanding the initiation and growth of plant tissues and organs. Although many TFs have been shown to have a role in the Arabidopsis root stem cells, a comprehensive view of the transcriptional signature of the stem cells is lacking. In this work, we used spatial and temporal transcriptomic data to predict interactions among the genes involved in stem cell regulation. To accomplish this, we transcriptionally profiled several stem cell populations and developed a gene regulatory network inference algorithm that combines clustering with dynamic Bayesian network inference. We leveraged the topology of our networks to infer potential major regulators. Specifically, through mathematical modeling and experimental validation, we identified PERIANTHIA (PAN) as an important molecular regulator of quiescent center function. The results presented in this work show that our combination of molecular biology, computational biology, and mathematical modeling is an efficient approach to identify candidate factors that function in the stem cells.
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Korn RW. Modelling the vasculature of the stem of Cyperus involucratus Rottb.: evidence for three patterns of vascular bundles. PLANTA 2016; 244:103-110. [PMID: 26969023 DOI: 10.1007/s00425-016-2495-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 02/22/2016] [Indexed: 06/05/2023]
Abstract
Three independent patterns of vein formation in Cyperus involucratus Rottb. were identified based on rare spontaneous interruptions of scape vein development. A number of developmental anomalies of vascular bundles in Cyperus involucratus Rottb. were identified and they include "turnabout", "absent", "twins", "doublet", amphivasal and various stages of "arrested". These were used to develop a computer program to explain the three vasculature patterns of the scape of (a) ordered deployment of vascular bundles, (b) arrangement of tissues within vascular bundles and (c) orientation of vascular bundles with respect to stem edge. The computer model is a cell-by-cell determination of cell types and facet states.
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Affiliation(s)
- Robert W Korn
- Biology Department, Bellarmine University, 2001 Newburg Rd., Louisville, KY, 40219, USA.
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Nieminen K, Blomster T, Helariutta Y, Mähönen AP. Vascular Cambium Development. THE ARABIDOPSIS BOOK 2015; 13:e0177. [PMID: 26078728 PMCID: PMC4463761 DOI: 10.1199/tab.0177] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Secondary phloem and xylem tissues are produced through the activity of vascular cambium, the cylindrical secondary meristem which arises among the primary plant tissues. Most dicotyledonous species undergo secondary development, among them Arabidopsis. Despite its small size and herbaceous nature, Arabidopsis displays prominent secondary growth in several organs, including the root, hypocotyl and shoot. Together with the vast genetic resources and molecular research methods available for it, this has made Arabidopsis a versatile and accessible model organism for studying cambial development and wood formation. In this review, we discuss and compare the development and function of the vascular cambium in the Arabidopsis root, hypocotyl, and shoot. We describe the current understanding of the molecular regulation of vascular cambium and compare it to the function of primary meristems. We conclude with a look at the future prospects of cambium research, including opportunities provided by phenotyping and modelling approaches, complemented by studies of natural variation and comparative genetic studies in perennial and woody plant species.
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Affiliation(s)
- Kaisa Nieminen
- Natural Resources Institute Finland (Luke), Green Technology, Vantaa 01301, Finland
| | - Tiina Blomster
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
- Department of Biosciences, University of Helsinki, Helsinki 00014, Finland
| | - Ykä Helariutta
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
- Department of Biosciences, University of Helsinki, Helsinki 00014, Finland
- The Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge CB2 1LR, UK
- Cardiff University Cardiff School of Biosciences, The Sir Martin Evans Building, Museum Avenue, Cardiff, CF10 3AX, UK
| | - Ari Pekka Mähönen
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
- Department of Biosciences, University of Helsinki, Helsinki 00014, Finland
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Celton JM, Dheilly E, Guillou MC, Simonneau F, Juchaux M, Costes E, Laurens F, Renou JP. Additional amphivasal bundles in pedicel pith exacerbate central fruit dominance and induce self-thinning of lateral fruitlets in apple. PLANT PHYSIOLOGY 2014; 164:1930-51. [PMID: 24550240 PMCID: PMC3982754 DOI: 10.1104/pp.114.236117] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Apple (Malus × domestica) trees naturally produce an excess of fruitlets that negatively affect the commercial value of fruits brought to maturity and impact their capacity to develop flower buds the following season. Therefore, chemical thinning has become an important cultural practice, allowing the selective removal of unwanted fruitlets. As the public pressure to limit the use of chemical agents increases, the control of thinning becomes a major issue. Here, we characterized the self-thinning capacity of an apple hybrid genotype from the tree scale to the molecular level. Additional amphivasal vascular bundles were identified in the pith of pedicels supporting the fruitlets with the lowest abscission potential (central fruitlet), indicating that these bundles might have a role in the acquisition of dominance over lateral fruitlets. Sugar content analysis revealed that central fruitlets were better supplied in sorbitol than lateral fruitlets. Transcriptomic profiles allowed us to identify genes potentially involved in the overproduction of vascular tissues in central pedicels. In addition, histological and transcriptomic data permitted a detailed characterization of abscission zone development and the identification of key genes involved in this process. Our data confirm the major role of ethylene, auxin, and cell wall-remodeling enzymes in abscission zone formation. The shedding process in this hybrid appears to be triggered by a naturally exacerbated dominance of central fruitlets over lateral ones, brought about by an increased supply of sugars, possibly through additional amphivasal vascular bundles. The characterization of this genotype opens new perspectives for the selection of elite apple cultivars.
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Porth I, Klápště J, McKown AD, La Mantia J, Hamelin RC, Skyba O, Unda F, Friedmann MC, Cronk QC, Ehlting J, Guy RD, Mansfield SD, El-Kassaby YA, Douglas CJ. Extensive functional pleiotropy of REVOLUTA substantiated through forward genetics. PLANT PHYSIOLOGY 2014; 164:548-54. [PMID: 24309192 PMCID: PMC3912088 DOI: 10.1104/pp.113.228783] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
In plants, genes may sustain extensive pleiotropic functional properties by individually affecting multiple, distinct traits. We discuss results from three genome-wide association studies of approximately 400 natural poplar (Populus trichocarpa) accessions phenotyped for 60 ecological/biomass, wood quality, and rust fungus resistance traits. Single-nucleotide polymorphisms (SNPs) in the poplar ortholog of the class III homeodomain-leucine zipper transcription factor gene REVOLUTA (PtREV) were significantly associated with three specific traits. Based on SNP associations with fungal resistance, leaf drop, and cellulose content, the PtREV gene contains three potential regulatory sites within noncoding regions at the gene's 3' end, where alternative splicing and messenger RNA processing actively occur. The polymorphisms in this region associated with leaf abscission and cellulose content are suggested to represent more recent variants, whereas the SNP associated with leaf rust resistance may be more ancient, consistent with REV's primary role in auxin signaling and its functional evolution in supporting fundamental processes of vascular plant development.
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Jover-Gil S, Candela H, Robles P, Aguilera V, Barrero JM, Micol JL, Ponce MR. The MicroRNA Pathway Genes AGO1, HEN1 and HYL1 Participate in Leaf Proximal–Distal, Venation and Stomatal Patterning in Arabidopsis. ACTA ACUST UNITED AC 2012; 53:1322-33. [DOI: 10.1093/pcp/pcs077] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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10
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The role of mobile small RNA species during root growth and development. Curr Opin Cell Biol 2012; 24:211-6. [PMID: 22227227 DOI: 10.1016/j.ceb.2011.12.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 11/26/2011] [Accepted: 12/08/2011] [Indexed: 11/21/2022]
Abstract
In animals and plants, small RNAs have been identified as important regulatory factors controlling cell fate. A bidirectional cell-to-cell communication involving the mobile transcription factor SHR and microRNA165/166 species specifies the radial position of two types of xylem vessels in Arabidopsis roots. The microRNAs provide short-range non-cell-autonomous developmental signals that are transported through the plasmodesmata (PD) via the symplastic pathway. 21-24 nucleotide-long small RNA species have been shown to move from the shoot to the root. In this review, we highlight the presence of small RNA species as an emerging class of important mobile signals associated with the growth and development of the root.
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Côté CL, Boileau F, Roy V, Ouellet M, Levasseur C, Morency MJ, Cooke JEK, Séguin A, MacKay JJ. Gene family structure, expression and functional analysis of HD-Zip III genes in angiosperm and gymnosperm forest trees. BMC PLANT BIOLOGY 2010; 10:273. [PMID: 21143995 PMCID: PMC3017839 DOI: 10.1186/1471-2229-10-273] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Accepted: 12/11/2010] [Indexed: 05/03/2023]
Abstract
BACKGROUND Class III Homeodomain Leucine Zipper (HD-Zip III) proteins have been implicated in the regulation of cambium identity, as well as primary and secondary vascular differentiation and patterning in herbaceous plants. They have been proposed to regulate wood formation but relatively little evidence is available to validate such a role. We characterised and compared HD-Zip III gene family in an angiosperm tree, Populus spp. (poplar), and the gymnosperm Picea glauca (white spruce), representing two highly evolutionarily divergent groups. RESULTS Full-length cDNA sequences were isolated from poplar and white spruce. Phylogenetic reconstruction indicated that some of the gymnosperm sequences were derived from lineages that diverged earlier than angiosperm sequences, and seem to have been lost in angiosperm lineages. Transcript accumulation profiles were assessed by RT-qPCR on tissue panels from both species and in poplar trees in response to an inhibitor of polar auxin transport. The overall transcript profiles HD-Zip III complexes in white spruce and poplar exhibited substantial differences, reflecting their evolutionary history. Furthermore, two poplar sequences homologous to HD-Zip III genes involved in xylem development in Arabidopsis and Zinnia were over-expressed in poplar plants. PtaHB1 over-expression produced noticeable effects on petiole and primary shoot fibre development, suggesting that PtaHB1 is involved in primary xylem development. We also obtained evidence indicating that expression of PtaHB1 affected the transcriptome by altering the accumulation of 48 distinct transcripts, many of which are predicted to be involved in growth and cell wall synthesis. Most of them were down-regulated, as was the case for several of the poplar HD-Zip III sequences. No visible physiological effect of over-expression was observed on PtaHB7 transgenic trees, suggesting that PtaHB1 and PtaHB7 likely have distinct roles in tree development, which is in agreement with the functions that have been assigned to close homologs in herbaceous plants. CONCLUSIONS This study provides an overview of HD-zip III genes related to woody plant development and identifies sequences putatively involved in secondary vascular growth in angiosperms and in gymnosperms. These gene sequences are candidate regulators of wood formation and could be a source of molecular markers for tree breeding related to wood properties.
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Affiliation(s)
- Caroline L Côté
- Département des Sciences du Bois et de la Forêt, Université Laval, 2405 rue de la Terrasse, Québec, QC G1V0A6, Canada
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12
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Smith ZR, Long JA. Control of Arabidopsis apical-basal embryo polarity by antagonistic transcription factors. Nature 2010; 464:423-6. [PMID: 20190735 PMCID: PMC2841697 DOI: 10.1038/nature08843] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Accepted: 01/08/2010] [Indexed: 11/16/2022]
Abstract
Plants, similar to animals, form polarized axes during embryogenesis upon which cell differentiation and organ patterning programs are orchestrated. During Arabidopsis embryogenesis, establishment of the shoot and root stem cell populations occurs at opposite ends of an apical-basal axis. Recent work has identified the PLETHORA (PLT) genes as master regulators of basal/root fate1–3, while the master regulators of apical/shoot fate have remained elusive. Here we show that the PLT1 and PLT2 genes are direct targets of the transcriptional corepressor TOPLESS (TPL) and that PLT1/2 are necessary for the homeotic conversion of shoots to roots in tpl-1 mutants. Using tpl-1 as a genetic tool, we identify the CLASS IIIHOMEODOMAIN-LEUCINE ZIPPER (HD-ZIP III) transcription factors as master regulators of embryonic apical fate, and show they are sufficient to drive the conversion of the embryonic root pole into a second shoot pole. Furthermore, genetic and misexpression studies reveal an antagonistic relationship between the PLT and HD-ZIP III genes in specifying the root and shoot pole.
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Affiliation(s)
- Zachery R Smith
- Plant Biology Laboratory, The Salk Institute for Biological Studies, University of California San Diego, La Jolla, California 92037, USA
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14
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Candela H, Johnston R, Gerhold A, Foster T, Hake S. The milkweed pod1 gene encodes a KANADI protein that is required for abaxial/adaxial patterning in maize leaves. THE PLANT CELL 2008; 20:2073-87. [PMID: 18757553 PMCID: PMC2553616 DOI: 10.1105/tpc.108.059709] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Revised: 07/15/2008] [Accepted: 07/31/2008] [Indexed: 05/19/2023]
Abstract
Leaf primordia initiate from the shoot apical meristem with inherent polarity; the adaxial side faces the meristem, while the abaxial side faces away from the meristem. Adaxial/abaxial polarity is thought to be necessary for laminar growth of leaves, as mutants lacking either adaxial or abaxial cell types often develop radially symmetric lateral organs. The milkweed pod1 (mwp1) mutant of maize (Zea mays) has adaxialized sectors in the sheath, the proximal part of the leaf. Ectopic leaf flaps develop where adaxial and abaxial cell types juxtapose. Ectopic expression of the HD-ZIPIII gene rolled leaf1 (rld1) correlates with the adaxialized regions. Cloning of mwp1 showed that it encodes a KANADI transcription factor. Double mutants of mwp1-R with a microRNA-resistant allele of rld1, Rld1-N1990, show a synergistic phenotype with polarity defects in sheath and blade and a failure to differentiate vascular and photosynthetic cell types in the adaxialized sectors. The sectored phenotype and timing of the defect suggest that mwp1 is required late in leaf development to maintain abaxial cell fate. The phenotype of mwp1; Rld1 double mutants shows that both genes are also required early in leaf development to delineate leaf margins as well as to initiate vascular and photosynthetic tissues.
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Affiliation(s)
- Héctor Candela
- Plant Gene Expression Center, US Department of Agriculture-Agricultural Research Service, Albany, California 94710, USA
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15
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Abstract
Arabidopsis class III homeodomain-leucine zipper (HD-Zip III) proteins play overlapping, distinct, and antagonistic roles in key aspects of development that have evolved during land plant evolution. To better understand this gene family's role in plant evolution and development as well as to address broader questions of how duplicated genes functionally diversify, we investigated the evolutionary history of this gene family. Phylogenetic analyses including homologs from diverse land plants indicate that a gene duplication event before the angiosperm--gymnosperm split gave rise to two gene lineages that diversified during angiosperm plant radiation. Heterologous expression of an HD-Zip III gene from the nonvascular plant moss within the Arabidopsis HD-zip III revoluta mutant modified but did not complement the phenotype. Comparison of the expression domains of flowering and nonflowering plant homologs indicate an ancestral role in vascular development and organ initiation but not in specifying organ polarity, a prominent role for angiosperm homologs.
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Affiliation(s)
- Michael J Prigge
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
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16
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Zhong R, Ye ZH. Regulation of HD-ZIP III Genes by MicroRNA 165. PLANT SIGNALING & BEHAVIOR 2007; 2:351-3. [PMID: 19704656 PMCID: PMC2634209 DOI: 10.4161/psb.2.5.4119] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Accepted: 03/07/2007] [Indexed: 05/13/2023]
Abstract
MicroRNAs (miRNAs) 165 and 166 are able to cleave their target mRNAs of HD-ZIP III genes, thus regulating the functions of these genes. Although it is generally accepted that both miR165 and miR166 perform the same functions in the regulation of HD-ZIP III genes in Arabidopsis, no experimental data are available to support this notion. Recent work has shown that overexpression of miR166 downregulates the expression of three HD-ZIP III genes, ATHB-9/PHV, ATHB-14/PHB and ATHB-15, which in turn recapitulates the phenotypes of simultaneous loss-of-function mutations of these genes. In the March issue of Plant & Cell Physiology, we have demonstrated that overexpression of miR165 leads to the down-regulation of all five HD-ZIP III genes, and concomitantly recapitulates the phenotypes of loss-of-function mutation of IFL1/REV and those of simultaneous loss-of-function mutations of IFL1/REV, ATHB-9/PHV and ATHB-14/PHB. These results indicate that miR165 and miR166 differentially regulate the functions of HD-ZIP III genes in Arabidopsis. In this addendum, we show that overexpression of the antisense form of the miR165a gene leads to formation of amphivasal vascular bundles, a phenotype reminiscent of that of the dominant mutation of IFL1/REV. This finding provides direct evidence for a role of miR165 in regulation of vascular patterning.
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Affiliation(s)
- Ruiqin Zhong
- Department of Plant Biology; University of Georgia; Athens, Georgia USA
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17
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Zhou GK, Kubo M, Zhong R, Demura T, Ye ZH. Overexpression of miR165 Affects Apical Meristem Formation, Organ Polarity Establishment and Vascular Development in Arabidopsis. ACTA ACUST UNITED AC 2007; 48:391-404. [PMID: 17237362 DOI: 10.1093/pcp/pcm008] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The class III homeodomain leucine-zipper (HD-ZIP III) genes are thought to be targets of microRNAs (miRNAs) 165 and 166, but it is not known whether all the developmental processes affected by mutations of the HD-ZIP III genes could be recapitulated by an alteration in the expression of miR165 and miR166. Previous work showed that overexpression of miR166 by activation tagging results in down-regulation of the ATHB-9/PHV, ATHB-14/PHB and ATHB-15 genes, and concomitantly causes an enlargement of shoot apical meristems (SAMs) and an enhancement in vascular development. Here we demonstrated that overexpression of miR165 causes a drastic reduction in the transcript levels of all five HD-ZIP III genes in Arabidopsis. The miR165 overexpressors display prominent phenotypes reminiscent of loss-of-function mutants of rev phb phv and rev/ifl1, including loss of SAM, alteration of organ polarity, abnormal formation of carpels, inhibition of vascular development and aberrant differentiation of interfascicular fibers. Global gene expression analysis revealed a link between miR165 overexpression and altered expression of genes involved in auxin signaling and vascular development. Our results demonstrate that overexpression of miR165 recapitulates the phenotypes caused by loss-of-function mutations of HD-ZIP III genes, such as loss of SAM, altered organ polarity and defects in development of vascular tissues and interfascicular fibers.
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Affiliation(s)
- Gong-Ke Zhou
- Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
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18
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Dengler NG. The shoot apical meristem and development of vascular architectureThis review is one of a selection of papers published on the Special Theme of Shoot Apical Meristems. ACTA ACUST UNITED AC 2006. [DOI: 10.1139/b06-126] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The shoot apical meristem (SAM) functions to generate external architecture and internal tissue pattern as well as to maintain a self-perpetuating population of stem-cell-like cells. The internal three-dimensional architecture of the vascular system corresponds closely to the external arrangement of lateral organs, or phyllotaxis. This paper reviews this correspondence for dicotyledonous plants in general and in Arabidopsis thaliana (L.) Heynh., specifically. Analysis is partly based on the expression patterns of the class III homeodomain-leucine zipper transcription factor ARABIDOPSIS THALIANA HOMEOBOX GENE 8 (ATHB8), a marker of the procambial and preprocambial stages of vascular development, and on the anatomical criteria for recognizing vascular tissue pattern. The close correspondence between phyllotaxis and vascular pattern present in mature tissues arises at early stages of development, at least by the first plastochron of leaf primordium outgrowth. Current literature provides an integrative model in which local variation in auxin concentration regulates both primordium formation on the SAM and the first indications of a procambial prepattern in the position of primordium leaf trace as well as in the elaboration of leaf vein pattern. The prospects for extending this model to the development of the complex three-dimensional vascular architecture of the shoot are promising.
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Affiliation(s)
- Nancy G. Dengler
- Department of Botany, University of Toronto, Toronto, ON M5S 1A1, Canada (e-mail: )
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19
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Imai A, Hanzawa Y, Komura M, Yamamoto KT, Komeda Y, Takahashi T. The dwarf phenotype of the Arabidopsis acl5 mutant is suppressed by a mutation in an upstream ORF of a bHLH gene. Development 2006; 133:3575-85. [PMID: 16936072 DOI: 10.1242/dev.02535] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Loss-of-function mutants of the Arabidopsis thaliana ACAULIS 5(ACL5) gene, which encodes spermine synthase, exhibit a severe dwarf phenotype. To elucidate the ACL5-mediated regulatory pathways of stem internode elongation, we isolated four suppressor of acaulis(sac) mutants that reverse the acl5 dwarf phenotype. Because these mutants do not rescue the dwarfism of known phytohormone-related mutants, the SAC genes appear to act specifically on the ACL5 pathways. We identify the gene responsible for the dominant sac51-d mutant, which almost completely suppresses the acl5phenotype. sac51-d disrupts a short upstream open reading frame(uORF) of SAC51, which encodes a bHLH-type transcription factor. Our results indicate that premature termination of the uORF in sac51-dresults in an increase in its own transcript level, probably as a result of an increased translation of the main ORF. We suggest a model in which ACL5 plays a role in the translational activation of SAC51,which may lead to the expression of a subset of genes required for stem elongation.
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Affiliation(s)
- Akihiro Imai
- Division of Bioscience, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
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20
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Ochando I, Jover-Gil S, Ripoll JJ, Candela H, Vera A, Ponce MR, Martínez-Laborda A, Micol JL. Mutations in the microRNA complementarity site of the INCURVATA4 gene perturb meristem function and adaxialize lateral organs in arabidopsis. PLANT PHYSIOLOGY 2006; 141:607-19. [PMID: 16617092 PMCID: PMC1475466 DOI: 10.1104/pp.106.077149] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2006] [Revised: 03/16/2006] [Accepted: 04/07/2006] [Indexed: 05/08/2023]
Abstract
Here, we describe how the semidominant, gain-of-function icu4-1 and icu4-2 alleles of the INCURVATA4 (ICU4) gene alter leaf phyllotaxis and cell organization in the root apical meristem, reduce root length, and cause xylem overgrowth in the stem. The ICU4 gene was positionally cloned and found to encode the ATHB15 transcription factor, a class III homeodomain/leucine zipper family member, recently named CORONA. The icu4-1 and icu4-2 alleles bear the same point mutation that affects the microRNA complementarity site of ICU4 and is identical to those of several semidominant alleles of the class III homeodomain/leucine zipper family members PHABULOSA and PHAVOLUTA. The icu4-1 and icu4-2 mutations significantly increase leaf transcript levels of the ICU4 gene. The null hst-1 allele of the HASTY gene, which encodes a nucleocytoplasmic transporter, synergistically interacts with icu4-1, the double mutant displaying partial adaxialization of rosette leaves and carpels. Our results suggest that the ICU4 gene has an adaxializing function and that it is down-regulated by microRNAs that require the HASTY protein for their biogenesis.
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Affiliation(s)
- Isabel Ochando
- División de Genética, Universidad Miguel Hernández, Campus de San Juan, 03550 Alicante, Spain
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21
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Pesquet E, Ranocha P, Legay S, Digonnet C, Barbier O, Pichon M, Goffner D. Novel markers of xylogenesis in zinnia are differentially regulated by auxin and cytokinin. PLANT PHYSIOLOGY 2005; 139:1821-39. [PMID: 16306148 PMCID: PMC1310562 DOI: 10.1104/pp.105.064337] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The characterization of in vitro xylogenic cultures of zinnia (Zinnia elegans) has led to major discoveries in the understanding of xylem formation in plants. We have constructed and characterized a subtractive library from zinnia cultures enriched in genes that are specifically expressed at the onset of secondary wall deposition and tracheary element (TE) programmed cell death. This Late Xylogenesis Library (LXL) consisted of 236 nonredundant cDNAs, 77% of which encoded novel sequences in comparison with the 17,622 expressed sequence tag sequences publicly available. cDNA arrays were constructed to examine dynamic global gene expression during the course of TE formation. As a first step in dissecting auxin and cytokinin signaling during TE differentiation, macroarrays were probed with cDNAs from cells cultured in different hormonal conditions. Fifty-one percent of the LXL genes were induced by either auxin or cytokinin individually, the large majority by auxin. To determine the potential involvement of these categories of genes in TE differentiation, multiplex in situ-reverse transcription-PCR was performed on cells for two genes encoding putative cell wall proteins: Gibberellin stimulated transcript-1, induced by auxin alone, and expansin 5, induced by cytokinin alone. All transcriptionally active TEs expressed both genes, indicating that, although these genes may not be considered as specific markers for TE differentiation per se, they are nevertheless an integral part of TE differentiation program. Among the non-TE population, four different gene expression-based cell types could be distinguished. Together, these results demonstrate the underlying complexity of hormonal perception and the existence of several different cell types in in vitro TE cell cultures.
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Affiliation(s)
- Edouard Pesquet
- Unité Mixte de Recherche, Centre National de la Recherche Scientifique/Université Paul Sabatier 5546, Surfaces Cellulaires et Signalisation chez les Végétaux, Pôle de Biotechnologie Végétale, 31326 Castanet, Tolosan, France
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22
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Carlsbecker A, Helariutta Y. Phloem and xylem specification: pieces of the puzzle emerge. CURRENT OPINION IN PLANT BIOLOGY 2005; 8:512-7. [PMID: 16039153 DOI: 10.1016/j.pbi.2005.07.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Accepted: 07/12/2005] [Indexed: 05/03/2023]
Abstract
The plant vascular system is composed of two tissue types, xylem and phloem, which originate from the vascular meristem, the procambium. Recently, several regulatory mechanisms that control the specification of these two tissue types have been uncovered. These include the asymmetric patterning of xylem and phloem in the vascular bundle by the class III HD-ZIP and KANADI genes, the tissue-type-specific control of vascular cell proliferation by brassinosteroids and class III HD-ZIP genes, the regulation of vascular tissue identity by the MYB-like transcription factor APL, and inductive signalling during xylem differentiation by xylogen. These findings define an emerging developmental framework for the control of vascular tissue specification.
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Affiliation(s)
- Annelie Carlsbecker
- Institute of Biotechnology, Viikinkaari 4, FI-00014 University of Helsinki, Finland
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23
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Ohashi-Ito K, Kubo M, Demura T, Fukuda H. Class III homeodomain leucine-zipper proteins regulate xylem cell differentiation. PLANT & CELL PHYSIOLOGY 2005; 46:1646-56. [PMID: 16081527 DOI: 10.1093/pcp/pci180] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Although it has been suggested that class III homeodomain leucine-zipper proteins (HD-Zip III) are involved in vascular development, details of the function of individual HD-Zip III proteins in vascular differentiation have not been resolved. To understand the function of each HD-Zip III protein in vascular differentiation precisely, we analyzed the in vitro transcriptional activity and in vivo function of Zinnia HD-Zip III genes, ZeHB-10, ZeHB-11 and ZeHB-12, which show xylem-related expression. Transgenic Arabidopsis plants harboring cauliflower mosaic virus 35S-driven ZeHB-10 and ZeHB-12 with a mutation in the START domain (mtZeHB-10, mtZeHB-12) showed a higher production of tracheary elements (TEs) and xylem precursor cells, respectively. A systematic analysis with Genechip arrays revealed that overexpression of mtZeHB-12 rapidly induced various genes, including brassinosteroid-signaling pathway-related genes and genes for transcription factors that are expressed specifically in vascular tissues in situ. Furthermore, mtZeHB-12 overexpression did not induce TE-specific genes, including genes related to programmed cell death and lignin polymerization, but did induce lignin monomer synthesis-related genes, which are expressed in xylem parenchyma cells. These results suggest that ZeHB-12 is involved in the differentiation of xylem parenchyma cells, but not of TEs.
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Affiliation(s)
- Kyoko Ohashi-Ito
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Japan.
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24
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Prigge MJ, Otsuga D, Alonso JM, Ecker JR, Drews GN, Clark SE. Class III homeodomain-leucine zipper gene family members have overlapping, antagonistic, and distinct roles in Arabidopsis development. THE PLANT CELL 2005; 17:61-76. [PMID: 15598805 PMCID: PMC544490 DOI: 10.1105/tpc.104.026161] [Citation(s) in RCA: 514] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2004] [Accepted: 10/10/2004] [Indexed: 05/18/2023]
Abstract
The Arabidopsis thaliana genome contains five class III homeodomain-leucine zipper genes. We have isolated loss-of-function alleles for each family member for use in genetic analysis. This gene family regulates apical embryo patterning, embryonic shoot meristem formation, organ polarity, vascular development, and meristem function. Genetic analyses revealed a complex pattern of overlapping functions, some of which are not readily inferred by phylogenetic relationships or by gene expression patterns. The PHABULOSA and PHAVOLUTA genes perform overlapping functions with REVOLUTA, whereas the PHABULOSA, PHAVOLUTA, and CORONA/ATHB15 genes perform overlapping functions distinct from REVOLUTA. Furthermore, ATHB8 and CORONA encode functions that are both antagonistic to those of REVOLUTA within certain tissues and overlapping with REVOLUTA in other tissues. Differences in expression patterns explain some of these genetic interactions, whereas other interactions are likely attributable to differences in protein function as indicated by cross-complementation studies.
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Affiliation(s)
- Michael J Prigge
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, An Arbor, Michigan 48109-1048, USA
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25
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Prigge MJ, Otsuga D, Alonso JM, Ecker JR, Drews GN, Clark SE. Class III homeodomain-leucine zipper gene family members have overlapping, antagonistic, and distinct roles in Arabidopsis development. THE PLANT CELL 2005. [PMID: 15598805 DOI: 10.1105/tpc.104.026161.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The Arabidopsis thaliana genome contains five class III homeodomain-leucine zipper genes. We have isolated loss-of-function alleles for each family member for use in genetic analysis. This gene family regulates apical embryo patterning, embryonic shoot meristem formation, organ polarity, vascular development, and meristem function. Genetic analyses revealed a complex pattern of overlapping functions, some of which are not readily inferred by phylogenetic relationships or by gene expression patterns. The PHABULOSA and PHAVOLUTA genes perform overlapping functions with REVOLUTA, whereas the PHABULOSA, PHAVOLUTA, and CORONA/ATHB15 genes perform overlapping functions distinct from REVOLUTA. Furthermore, ATHB8 and CORONA encode functions that are both antagonistic to those of REVOLUTA within certain tissues and overlapping with REVOLUTA in other tissues. Differences in expression patterns explain some of these genetic interactions, whereas other interactions are likely attributable to differences in protein function as indicated by cross-complementation studies.
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Affiliation(s)
- Michael J Prigge
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, An Arbor, Michigan 48109-1048, USA
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26
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Scarpella E, Meijer AH. Pattern formation in the vascular system of monocot and dicot plant species. THE NEW PHYTOLOGIST 2004; 164:209-242. [PMID: 33873557 DOI: 10.1111/j.1469-8137.2004.01191.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Plant vascular tissues are organised in continuous strands, the longitudinal and radial patterns of which are intimately linked to the signals that direct plant architecture as a whole. Therefore, understanding the mechanisms underlying vascular tissue patterning is expected to shed light on patterning events beyond those that organise the vascular system, and thus represents a central issue in plant developmental biology. A number of recent advances, reviewed here, are leading to a more precise definition of the signals that control the formation of vascular tissues and their integration into a larger organismal context. Contents Summary 209 I. Introduction 209 II. The plant vascular system 210 III. Ontogeny of the vascular tissues 210 IV. Procambium development 210 V. The organisation of the vascular tissues 212 VI. The regulation of longitudinal vascular pattern formation 214 VII. The regulation of radial vascular pattern formation 220 VIII. Genetic screens for vascular development mutants 231 IX. Genes involved in vascular development identified through reverse genetics approaches 235 X. Conclusions and perspectives 235 Note added at the revision stage 236 Acknowledgements 236 References 236.
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Affiliation(s)
- Enrico Scarpella
- Department of Botany, University of Toronto, 25 Willcocks Street, Toronto ON, Canada M5S 3B2
- Department of Biological Sciences, University of Alberta, CW405 Biological Sciences Building, Edmonton AB, Canada T6G 2E9
| | - Annemarie H Meijer
- Insitute of Biology, Leiden University, Clusius Laboratory, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands
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27
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Nieminen KM, Kauppinen L, Helariutta Y. A weed for wood? Arabidopsis as a genetic model for xylem development. PLANT PHYSIOLOGY 2004; 135:653-9. [PMID: 15208411 PMCID: PMC514101 DOI: 10.1104/pp.104.040212] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2004] [Revised: 04/04/2004] [Accepted: 04/05/2004] [Indexed: 05/18/2023]
Affiliation(s)
- Kaisa M Nieminen
- Plant Molecular Biology Laboratory, Institute of Biotechnology, FI-00014 University of Helsinki, Finland
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28
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Zhong R, Ye ZH. amphivasal vascular bundle 1, a Gain-of-Function Mutation of the IFL1/REV Gene, Is Associated with Alterations in the Polarity of Leaves, Stems and Carpels. ACTA ACUST UNITED AC 2004; 45:369-85. [PMID: 15111711 DOI: 10.1093/pcp/pch051] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
In Arabidopsis stems, the vascular bundles in the stele are arranged in a ring-like pattern and the vascular tissues in each bundle are organized in a collateral pattern. We have shown previously that the semidominant amphivasal vascular bundle 1 (avb1) mutation transforms the collateral vascular bundles into amphivasal bundles and disrupts the ring-like arrangement of vascular bundles in the stele. In this study, we show that the avb1 mutation occurred in the putative microRNA 165 target sequence in the IFL1/REV gene and caused an amino acid substitution in the putative sterol/lipid-binding START domain. We present direct evidence that the wild-type IFL1/REV mRNA was cleaved within the microRNA 165 target sequence and the avb1 mutation resulted in an inhibition of cleavage and a higher level accumulation of full-length mRNA, suggesting a role of microRNA 165 in the regulation of IFL1/REV gene expression. In addition to an alteration in vascular patterning, the avb1 mutation also caused dramatic changes in fiber cell wall thickening and organ polarity, including aberrant formation and proliferation of cauline leaves and branches, production of trumpet-shaped leaves with reversed adaxial-abaxial identity, ectopic growth of carpel-like structures on the outer surface of carpels, and fasciation of inflorescence. Ectopic overexpression of the avb1 mutant cDNA not only phenocopied most of the avb1 mutant phenotypes but also led to additional novel phenotypes such as formation of leaves with extremely narrow blades and ectopic production of branches in the axil of siliques. Taken together, these results suggest that the avb1 gain-of-function mutation of the IFL1/REV gene alters the positional information that determines vascular patterning and organ polarity.
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Affiliation(s)
- Ruiqin Zhong
- Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
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29
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Emery JF, Floyd SK, Alvarez J, Eshed Y, Hawker NP, Izhaki A, Baum SF, Bowman JL. Radial Patterning of Arabidopsis Shoots by Class III HD-ZIP and KANADI Genes. Curr Biol 2003; 13:1768-74. [PMID: 14561401 DOI: 10.1016/j.cub.2003.09.035] [Citation(s) in RCA: 768] [Impact Index Per Article: 36.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Shoots of all land plants have a radial pattern that can be considered to have an adaxial (central)-abaxial (peripheral) polarity. In Arabidopsis, gain-of-function alleles of PHAVOLUTA and PHABULOSA, members of the class III HD-ZIP gene family, result in adaxialization of lateral organs. Conversely, loss-of-function alleles of the KANADI genes cause an adaxialization of lateral organs. Thus, the class III HD-ZIP and KANADI genes comprise a genetic system that patterns abaxial-adaxial polarity in lateral organs produced from the apical meristem. RESULTS We show that gain-of-function alleles of REVOLUTA, another member of the class III HD-ZIP gene family, are characterized by adaxialized lateral organs and alterations in the radial patterning of vascular bundles in the stem. The gain-of-function phenotype can be obtained by changing only the REVOLUTA mRNA sequence and without changing the protein sequence; this finding indicates that this phenotype is likely mediated through an interference with microRNA binding. Loss of KANADI activity results in similar alterations in vascular patterning as compared to REVOLUTA gain-of-function alleles. Simultaneous loss-of-function of PHABULOSA, PHAVOLUTA, and REVOLUTA abaxializes cotyledons, abolishes the formation of the primary apical meristem, and in severe cases, eliminates bilateral symmetry; these phenotypes implicate these three genes in radial patterning of both embryonic and postembryonic growth. CONCLUSIONS Based on complementary vascular and leaf phenotypes of class III HD-ZIP and KANADI mutants, we propose that a common genetic program dependent upon miRNAs governs adaxial-abaxial patterning of leaves and radial patterning of stems in the angiosperm shoot. This finding implies that a common patterning mechanism is shared between apical and vascular meristems.
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Affiliation(s)
- John F Emery
- Section of Plant Biology, University of California, Davis, Davis, CA 95616, USA
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30
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Parker G, Schofield R, Sundberg B, Turner S. Isolation of COV1, a gene involved in the regulation of vascular patterning in the stem of Arabidopsis. Development 2003; 130:2139-48. [PMID: 12668628 DOI: 10.1242/dev.00441] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The molecular mechanisms that control the ordered patterning of vascular tissue development in plants are not well understood. Several models propose a two-component system for vascular differentiation. These components include an inducer of vascular tissue development and an inhibitor that prevents the formation of vascular bundles near pre-existing bundles. We have identified two recessive allelic mutants in Arabidopsis, designated continuous vascular ring (cov1), that display a dramatic increase in vascular tissue development in the stem in place of the interfascicular region that normally separates the vascular bundles. The mutant plants exhibited relatively normal vascular patterning in leaves and cotyledons. Analysis of the interaction of cov1 with a known auxin signalling mutant and direct analysis of auxin concentrations suggests that cov1 affects vascular pattering by some mechanism that is independent of auxin. The COV1 protein is predicted to be an integral membrane protein of unknown function, highly conserved between plants and bacteria. In plants, COV1 is likely to be involved in a mechanism that negatively regulates the differentiation of vascular tissue in the stem.
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Affiliation(s)
- Garry Parker
- School of Biological Sciences, The University of Manchester, 3.614 Stopford Building, Oxford Road, Manchester M13 9PT, UK
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31
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Affiliation(s)
- Simon Turner
- School of Biological Science, University of Manchester, Manchester, UK;
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32
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Ye ZH, Freshour G, Hahn MG, Burk DH, Zhong R. Vascular development in Arabidopsis. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 220:225-56. [PMID: 12224550 DOI: 10.1016/s0074-7696(02)20007-8] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Vascular tissues, xylem and phloem, form a continuous network throughout the plant body for transport of water, minerals, and food. Characterization of Arabidopsis mutants defective in various aspects of vascular formation has demonstrated that Arabidopsis is an ideal system for investigating the molecular mechanisms controlling vascular development. The processes affected in these mutants include initiation or division of procambium or vascular cambium, formation of continuous vascular cell files, differentiation of procambium or vascular cambium into vascular tissues, cell elongation, patterned secondary wall thickening, and biosynthesis of secondary walls. Identification of the genes affected by some of these mutations has revealed essential roles in vascular development for a cytokinin receptor and several factors mediating auxin transport or signaling. Mutational studies have also identified a number of Arabidopsis mutants defective in leaf venation pattern or vascular tissue organization in stems. Genetic evidence suggests that the vascular tissue organization is regulated by the same positional information that determines organ polarity.
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Affiliation(s)
- Zheng-Hua Ye
- Department of Plant Biology, University of Georgia, Athens 30602, USA
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Booker J, Chatfield S, Leyser O. Auxin acts in xylem-associated or medullary cells to mediate apical dominance. THE PLANT CELL 2003; 15:495-507. [PMID: 12566587 PMCID: PMC141216 DOI: 10.1105/tpc.007542] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2002] [Accepted: 11/25/2002] [Indexed: 05/17/2023]
Abstract
A role for auxin in the regulation of shoot branching was described originally in the Thimann and Skoog model, which proposes that apically derived auxin is transported basipetally directly into the axillary buds, where it inhibits their growth. Subsequent observations in several species have shown that auxin does not enter axillary buds directly. We have found similar results in Arabidopsis. Grafting studies indicated that auxin acts in the aerial tissue; hence, the principal site of auxin action is the shoot. To delineate the site of auxin action, the wild-type AXR1 coding sequence, which is required for normal auxin sensitivity, was expressed under the control of several tissue-specific promoters in the auxin-resistant, highly branched axr1-12 mutant background. AXR1 expression in the xylem and interfascicular schlerenchyma was found to restore the mutant branching to wild-type levels in both intact plants and isolated nodes, whereas expression in the phloem did not. Therefore, apically derived auxin can suppress branching by acting in the xylem and interfascicular schlerenchyma, or in a subset of these cells.
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Affiliation(s)
- Jonathan Booker
- The Plant Laboratory, Department of Biology, University of York, P.O. Box 373, York YO10 5YW, United Kingdom
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Scarpella E, Rueb S, Meijer AH. The RADICLELESS1 gene is required for vascular pattern formation in rice. Development 2003; 130:645-58. [PMID: 12505996 DOI: 10.1242/dev.00243] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The molecular mechanisms through which the complex patterns of plant vascular tissues are established are largely unknown. The highly ordered, yet simple, striate array of veins of rice leaves represents an attractive system to study the dynamics underlying pattern formation. Here we show that mutation in the RADICLELESS1 (RAL1) gene results in distinctive vascular pattern defects. In ral1 embryonic scutella, secondary veins are absent and in the prematurely aborted and discontinuous primary veins, cells are misaligned to each other. In ral1 leaves, longitudinal and commissural (transverse) veins display altered spacing and the commissural veins additionally show atypical branching and interruptions in their continuity. The vascular pattern alterations of ral1 occur in the context of normally shaped leaf primordia. Anatomical inspection and analysis of the expression of the procambium specification marker Oshox1-GUS and of the auxin-inducible reporter DR5-GUS demonstrates that all the vascular patterning aberrations of ral1 originate from defects in the procambium, which represents the earliest identifiable stage of vascular development. Furthermore, the ral1 mutant is unique in that procambium formation in leaf primordium development is delayed. Finally, the ral1 vascular patterning distortions are associated with a defective response to auxin and with an enhanced sensitivity to cytokinin. ral1 is the first mutant impaired in both procambium development and vascular patterning to be isolated in a monocot species.
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Affiliation(s)
- Enrico Scarpella
- Institute of Molecular Plant Sciences, Leiden University, Clusius Laboratory, PO Box 9505, 2300 RA Leiden, The Netherlands
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35
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Chaffey N, Cholewa E, Regan S, Sundberg B. Secondary xylem development in Arabidopsis: a model for wood formation. PHYSIOLOGIA PLANTARUM 2002; 114:594-600. [PMID: 11975734 DOI: 10.1034/j.1399-3054.2002.1140413.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Our understanding of the molecular controls regulating the identity of the vascular cambium and the development of secondary xylem and phloem have not yet benefited much from the use of Arabidopsis as a genetic system. Under appropriate growth conditions Arabidopsis undergoes extensive secondary growth in the hypocotyl, with the development of both a vascular and a cork cambium. The secondary xylem of the hypocotyl develops in two phases, an early phase in which only vessel elements mature and a later stage in which both vessel elements and fibres are found. During this second phase the secondary xylem of Arabidopsis closely resembles the anatomy of the wood of an angiosperm tree, and can be used to address basic questions about wood formation. The development of the vascular cambium and secondary growth in Arabidopsis hypocotyl is described and its utility as a model for wood formation in trees is considered.
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Affiliation(s)
- Nigel Chaffey
- Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-901 83 Umeå, Sweden 1Present address: School of Science and Environment, Bath Spa University College, Newton Park, Newton St Loe, Bath BA2 9BN, UK 2Present address: Department of Biology, College of Natural Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
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36
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Abstract
Vascular tissues, xylem and phloem, are differentiated from meristematic cells, procambium, and vascular cambium. Auxin and cytokinin have been considered essential for vascular tissue differentiation; this is supported by recent molecular and genetic analyses. Xylogenesis has long been used as a model for study of cell differentiation, and many genes involved in late stages of tracheary element formation have been characterized. A number of mutants affecting vascular differentiation and pattern formation have been isolated in Arabidopsis. Studies of some of these mutants have suggested that vascular tissue organization within the bundles and vascular pattern formation at the organ level are regulated by positional information.
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Affiliation(s)
- Zheng-Hua Ye
- Department of Botany, University of Georgia, Athens, Georgia 30602, USA.
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Zhong R, Ye ZH. Alteration of auxin polar transport in the Arabidopsis ifl1 mutants. PLANT PHYSIOLOGY 2001; 126:549-63. [PMID: 11402186 PMCID: PMC111148 DOI: 10.1104/pp.126.2.549] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2001] [Accepted: 01/29/2001] [Indexed: 05/18/2023]
Abstract
The INTERFASCICULAR FIBERLESS/REVOLUTA (IFL1/REV) gene is essential for the normal differentiation of interfascicular fibers and secondary xylem in the inflorescence stems of Arabidopsis. It has been proposed that IFL1/REV influences auxin polar flow or the transduction of auxin signal, which is required for fiber and vascular differentiation. Assay of auxin polar transport showed that the ifl1 mutations dramatically reduced auxin polar flow along the inflorescence stems and in the hypocotyls. The null mutant allele ifl1-2 was accompanied by a significant decrease in the expression level of two putative auxin efflux carriers. The ifl1 mutants remained sensitive to auxin and an auxin transport inhibitor. The ifl1-2 mutant exhibited visible phenotypes associated with defects in auxin polar transport such as pin-like inflorescence, reduced numbers of cauline branches, reduced numbers of secondary rosette inflorescence, and dark green leaves with delayed senescence. The visible phenotypes displayed by the ifl1 mutants could be mimicked by treatment of wild-type plants with an auxin polar transport inhibitor. In addition, the auxin polar transport inhibitor altered the normal differentiation of interfascicular fibers in the inflorescence stems of wild-type Arabidopsis. Taken together, these results suggest a correlation between the reduced auxin polar transport and the alteration of cell differentiation and morphology in the ifl1 mutants.
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Affiliation(s)
- R Zhong
- Department of Botany, University of Georgia, Athens, Georgia 30602, USA
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38
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Abstract
Morphogenesis of leaf shape and formation of the major elements of leaf vasculature are temporally coordinated during leaf development. Current analyses of mutant phenotypes provide strong support for the role of auxin signaling in vascular pattern formation and indicate that leaf shape and vasculature are developmentally coupled. Two other mechanisms that may contribute to the regulation of these processes are a diffusion-reaction system and long-distance signaling of informational macromolecules.
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Affiliation(s)
- N Dengler
- Department of Botany, University of Toronto, 25 Willcocks Street, Ontario, M5S 3B2, Toronto, Canada.
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Huang S, Cerny RE, Bhat DS, Brown SM. Cloning of an Arabidopsis patatin-like gene, STURDY, by activation T-DNA tagging. PLANT PHYSIOLOGY 2001; 125:573-84. [PMID: 11161015 PMCID: PMC64859 DOI: 10.1104/pp.125.2.573] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2000] [Revised: 08/16/2000] [Accepted: 09/26/2000] [Indexed: 05/19/2023]
Abstract
Activation T-DNA tagging can generate dominant gain-of-function mutants by overexpression of a particular endogenous gene. We identified an activation-tagged mutant, sturdy, exhibiting a stiff inflorescence stem, thicker leaves, shorter siliques, larger seeds, round-shaped flowers, and delayed growth. It is most important that unlike its wild-type counterpart, this mutant is less prone to lodging. Cloning of STURDY revealed that in sturdy, there is an open reading frame containing a single intron encoding a patatin-like homolog. The T-DNA is inserted into the 3' region of the second exon. The mutant phenotype was shown to be the result of overexpression of STURDY by mRNA analysis and transgenic studies. Preliminary histological studies have revealed an increase in cell number in the inflorescence stem of mutant plants; however, additional studies are needed to better understand the overexpression phenotype.
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Affiliation(s)
- S Huang
- Mystic Research, Monsanto Company, 62 Maritime Drive, Mystic, Connecticut 06355, USA.
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40
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Xylem Formation and Lignification in Trees and Model Species. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s0921-0423(01)80051-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
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41
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Abstract
Xylogenesis is a complex developmental process culminating in programmed cell death as a truly terminal differentiation event. In Arabidopsis, the availability of vascular-patterning mutants, and the identification of genes and their products that are involved in cell specification, secondary-wall deposition and lignification, are providing clues to the functions of some of the sequences in the large expressed sequence tag databases derived from the xylem-rich tissues of trees. An in vitro system, the Zinnia mesophyll cell system, provides an alternative system for those cell-biological experiments that are difficult to tackle in intact plants. In particular, a combination of molecular-genetic and cell-biological approaches has made possible the elucidation of some of the features of plant programmed cell death.
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Affiliation(s)
- K Roberts
- Department of Cell Biology, John Innes Centre, Norwich Research Park, Colney, NR4 7UH, Norwich, UK.
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42
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Abstract
Plant vascular tissues form systems of interconnected cell files throughout the plant body. Vascular tissues usually differentiate at predictable positions but the wide range of functional patterns generated in response to abnormal growth conditions or wounding reveals partially self-organizing patterning mechanisms. Signals ensuring aligned cell differentiation within vascular strands are crucial in self-organized vascular patterning, and the apical-basal flow of indole acetic acid has been suspected to act as an orienting signal in this process. Several recent advances appear to converge on a more precise definition of the role of auxin flow in vascular tissue patterning.
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Affiliation(s)
- T Berleth
- Dept of Botany, University of Toronto,25 Willcocks Street, Toronto, Canada M5 S3 B2.
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